1. Field
The present disclosure relates to thermosensitive copolymers, forward osmosis water treatment devices including the same, and methods of producing and using the same.
2. Description of the Related Art
Osmosis (or forward osmosis) refers to a phenomenon wherein water moves from a lower solute concentration solution to a solution of a higher solute concentration by osmotic pressure. Reverse osmosis is a method of artificially applying pressure to move water in the opposite direction.
Desalination through reverse osmosis is a known technique in the field of water treatment. Reverse osmosis desalination involves artificially applying a relatively high pressure and thus entails relatively high energy consumption. To increase energy efficiency, a forward osmosis process using the principle of osmotic pressure has been suggested, and as a solute for the osmosis draw solution, ammonium bicarbonate, sulfur dioxide, aliphatic alcohols, aluminum sulfate, glucose, fructose, potassium nitrate, and the like have been used. Among them, an ammonium bicarbonate draw solution is most commonly used and after the forward osmosis process, the draw solute (i.e., ammonium bicarbonate) may undergo decomposition into ammonia and carbon dioxide at a temperature of about 60° C. and be removed. Further, newly suggested draw solutes include magnetic nanoparticles having hydrophilic polymers such as peptides and low molecular weight materials attached thereto (that can be separated by a magnetic field), a polymer electrolyte such as a dendrimer (that can be separated by a UF or NF membrane), and the like.
Because decomposition of ammonium bicarbonate requires heating at about 60° C. or higher, removal of the draw solute including this compound entails a relatively high level of energy consumption. In addition, because a complete elimination of ammonia is difficult (if not impossible), water produced by forward osmosis using ammonium bicarbonate as the draw solute is not suitable for drinking water due to the odor of ammonia. Meanwhile, magnetic nanoparticles present difficulties in terms of redispersing the agglomerated particles being separated from the draw solution by using a magnetic field. It is also difficult (if not impossible) to completely remove the nanoparticles. Thus, the toxicity of the nanoparticles may pose additional problems. In addition, as the thermosensitive dendrimers or the magnetic nanoparticles coated with a hydrophilic polymer or a low molecular weight substance have a size ranging from several nanometers to tens of nanometers, filters such as a nanofiltration or ultrafiltration membrane may be required. Moreover, there may be difficulties in terms of redispersion after being agglomerated.